Text-book on Practical Astronomy

accurate apparent approximate astronomical astronomical transit azimuth Cassiopeia celestial sphere centre Ceti chronometer circumpolar stars computed constellations coördinates Corr culmination Decl declination determined Diff earth east ecliptic elongation engineer's transit Engineering Ephemeris Equa equal altitudes equator equinox error Example formula given Greenwich Mean Greenwich Mean Noon horizontal angle horizontal axis horizontal cross hair hour angle hour circle hourly change index correction instant instrument interval Large 12mo latitude line of sight longitude lower limb mean solar mean sun measured meridian altitude method moon moon's motion Nautical Almanac nearly necessary Observed altitude obtained orbit parallax plane polar distance Polaris pole position refraction correction result right ascension sec h semidiameter sidereal day sight line sin Po spirit level star's subtracting sun's surface surveyor Table tangent telescope tide tion true tude vernier vertical arc vertical axis vertical circle vertical cross hair watch correction zenith distance ΙΟ